Strongly Coupled Cyclometalated Ruthenium Triarylamine Chromophores as Sensitizers for DSSCs. Issue 26 (19th May 2016)

• Record Type: Journal Article
• Authors: Kreitner, Christoph; Mengel, Andreas K. C.; Lee, Tae Kyung; Cho, Woohyung; Char, Kookheon; Kang, Yong Soo; Heinze, Katja
• Is Part Of: Chemistry. Volume 22:Issue 26(2016)
• Page Start: 8915
• Page End: 8928
• Publication Date: 2016-05-19
• Subjects: cobalt electrolytes -- cyclometalated complexes -- dye-sensitized solar cells -- mixed valency -- ruthenium; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201601001
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: A series of anchor‐functionalized cyclometalated bis(tridentate) ruthenium(II) triarylamine hybrids [Ru(dbp‐X)(tctpy)] 2− [2 a ] 2− –[2 c ] 2− (H3 tctpy=2, 2′;6′, 2′′‐terpyridine‐4, 4′, 4′′‐tricarboxylic acid; dpbH=1, 3‐dipyridylbenzene; X=N(4‐C6 H4 OMe)2 ([2 a ] 2− ), NPh2 ([2 b ] 2− ), N ‐carbazolyl [2 c ] 2− ) was synthesized and characterized. All complexes show broad absorption bands in the range 300–700 nm with a maximum at about 545 nm. Methyl esters [Ru(Me3 tctpy)(dpb‐X)] + [1 a ] + –[1 c ] + are oxidized to the strongly coupled mixed‐valent species [1 a ] 2+ –[1 c ] 2+ and the Ru III (aminium) complexes [1 a ] 3+ –[1 c ] 3+ at comparably low oxidation potentials. Theoretical calculations suggest an increasing spin delocalization between the metal center and the triarylamine unit in the order [1 a ] 2+ <[1 b ] 2+ <[1 c ] 2+ . Solar cells were prepared with the saponified complexes [2 a ] 2− –[2 c ] 2− and the reference dyeN719 as sensitizers using the I3 − /I − couple and [Co(bpy)3 ] 3+/2+ and [Co(ddpd)2 ] 3+/2+ couples as [B(C6 F5 )4 ] − salts as electrolytes (bpy=2, 2′‐bipyridine; ddpd= N, N ′‐dimethyl‐ N, N ′‐dipyridin‐2‐yl‐pyridine‐2, 6‐diamine). Cells with [2 c ] 2− and I3 − /I − electrolyte perform similarly to cells withN719 . In the presence of cobalt electrolytes, all efficiencies are reduced, yet under these conditions [2 c ] 2− outperformsN719 . Abstract : Anchor‐functionalized cyclometalated bis(tridentate) ruthenium(II) triarylamine hybrids featuring mixed‐valent states of varying resonance stabilization were employed in dye‐sensitized solar cells (DSSCs) in combination with different electrolytes. Together with cobalt‐based electrolytes, the N ‐carbazole substituted dye surpasses theN719 dye.